检索结果-内蒙古大学图书馆

Physical limits on chemical sensing in bounded domains

Physical Review E 2025年第3期111卷 034404-034404页

作者： Daniel R. McCusker David K. Lubensky Applied Physics Graduate Program University of Michigan Ann Arbor Michigan 48109 USA

Cells respond to chemical signals, and the precision with which they can sense these signals is fundamentally limited by the stochastic nature of diffusion and ligand binding. Berg and Purcell famously investigated how well a small sensor in an infinite ligand bath can determine the ligand concentration, and a number of subsequent analyses have refined and built upon their classical estimates. Not all concentration-sensing problems, however, occur in such an infinite geometry. At different scales, subcellular sensors and cells in tissues are both often confronted with signals whose diffusion is affected by confining boundaries. It is thus valuable to understand how basic limits on chemosensation depend on the sensor's size and on its position in the domain in which ligand diffuses. Here we compute how sensor size and proximity to reflecting boundaries affect the diffusion-limited precision of chemosensation for various geometries in one and three dimensions. We derive analytical expressions for the sensing limit in these geometries. Among our conclusions is the surprising result that, in certain circumstances, smaller sensors can be more effective than larger sensors. This effect arises from a trade-off between spatial averaging and time averaging that we analyze in detail. We also find that proximity to confining boundaries can degrade a sensor's precision significantly compared to the precision of the same sensor far from any boundaries.

关键词： Ligands

来源：评论

学校读者我要写书评

暂无评论

Efficiency of Eggshell Waste as a Metal Corrosion Inhibitor SS316L Based on Green Technology in Seawater Media 1

Efficiency of Eggshell Waste as a Metal Corrosion Inhibitor ...

引用

1st Engineering and Science International Conference 2024, ESIC 2024

作者： Alfattah, M. Arwati, I.G.A. Arramel Afkauni, A.A. Yofatama, R.M. Mechanical Engineering Program Engineering Faculty Mercu Buana University Jakarta Indonesia Center of Excellence Applied Physics and Chemistry Nano Center Indonesia Tangerang Indonesia Main Secretariat National Research and Innovation Agency Tangerang Indonesia

Utilizing eco-friendly inhibitors offers an effective approach to combat pipe corrosion, as focus has increasingly turned towards options that are cost-effective, environmentally benign. The research investigates the application of waste from domestic chicken eggshells as a corrosion inhibitor. The objective of this study is to evaluate the effectiveness, morphology, and chemical properties of 316L stainless steel when treated with these eggshell-based inhibitors. The study employed several techniques, including EPD coating, potentiodynamic polarization, SEM, and Raman spectroscopy in seawater. The findings indicated that the lowest corrosion rate was observed in specimens treated with a 14g inhibitor concentration, with an average rate of 6.24883x10-4 mmpy with the efficiency 96.09%. Analysis SEM revealed that the sample without any inhibitors exhibited numerous small cavities on its surface. In contrast, the sample with a 14g inhibitor concentration showed a reduction in these cavities and a darker surface appearance due to the presence of a layer of adsorbed eggshell powder. Raman spectroscopy of the samples treated with 14 grams of eggshell powder, the final product of corrosion has disappeared, but there is still a α-FeOOH feature and its intensity is greatly reduced. drastic. This signifies that the use of an eggshell coating has effectively prevented corrosion. © 2025 Institute of physics Publishing. All rights reserved.

关键词： Seawater corrosion

来源：评论

学校读者我要写书评

暂无评论

Hydrogen and deuterium tunneling in niobium

引用

Physical Review B 2025年第2期111卷 L020103-L020103页

作者： Abdulaziz Abogoda W. A. Shelton I. Vekhter J. A. Sauls Hearne Institute for Theoretical Physics Louisiana State University Baton Rouge Louisiana 70803 USA Applied Physics Graduate Program Northwestern University Evanston Illinois 60208 USA Department of Physics and Astronomy Louisiana State University Baton Rouge Louisiana 70803 USA

We use density functional methods to identify the atomic configurations of H and D atoms trapped by O impurities embedded in bulk Nb. The O atoms are located at the octahedral position in the Nb body-centered cubic (BCC) lattice, and H (D) atoms tunnel between two degenerate tetrahedral sites separated by a mirror plane. Using nudged elastic band (NEB) methods, we calculate the double-well potential for O-H and O-D impurities and the wave functions and tunnel splittings for H and D atoms. Our results agree with those obtained from analysis of heat capacity and neutron scattering measurements on Nb with low concentrations of O-H and O-D.

关键词： Atoms

来源：评论

学校读者我要写书评

暂无评论

Structural instability and charge transfer mediated transition in Pr3Co4Sn13: A synchrotron radiation based scattering and spectroscopic study

引用

Physical Review B 2025年第16期111卷 165119-165119页

作者： Surajit Ghosh Chin-Wei Li Chih-En Hsu Yu-Hui Liang Wei-Xuan Lin Kuan-Hung Chen Hsio-Tsu Wang Chao-Hung Du Jau-Wern Chiou Department of Physics Tamkang University New Taipei City 251 Taiwan Bachelor's Program in Advanced Materials Science Tamkang University New Taipei City 251 Taiwan Department of Applied Physics National University of Kaohsiung Kaohsiung 811 Taiwan

This study aims to clarify the physics of the transition that is observed in Pr3Co4Sn13 (PCS) by specific heat at ∼138 K, which resembles the formation of a charge density wave (CDW). The work is performed using synchrotron radiation based scattering and spectroscopic techniques that include temperature-dependent x-ray diffraction (XRD), x-ray scattering (XRS), x-ray absorption near-edge structure (XANES)/extended x-ray absorption fine structure (EXAFS), resonant inelastic x-ray spectroscopy (RIXS), valence-band photoemission (VB-PES), and first-principles calculation. The appearance of satellite features in the XRD and XRS studies revealed a modulation of the structure along a new q vector (0.5,0.5,0) below 120 K. Phonon calculations suggest softening of a phonon mode and a possible superlattice transition at low temperatures. The XANES spectra of the Sn K, Co L3,2, and Pr M5,4 edge revealed an increase of charge transfer (CT) at low temperatures as a result of an enhancement of Co3d−Sn5p/Pr4f, and Pr4f−Sn5p hybridizations. The EXAFS study at the Sn K edge further suggested local distortion of the Sn sites because of Sn-Sn bond elongation at low temperatures. The VB-PES study and theoretical calculations that are based on spin-polarized density functional theory together confirm the strength of hybridization and the lack of any significant change in the band gap of the PCS with temperatures. The RIXS spectra at the Co L3 edge provide further evidence of the CT process, and the energy level of Co 3d states below the Fermi level were found to be static in the temperature range of 80 to 300 K, implying no change in the band gap of the PCS with temperatures. Based on the relevant results, the appearance of a clear kink around 138 K in the temperature-dependent specific heat measurements is caused by local lattice distortion at the Sn sites by a diffusionless mechanism, resulting in minimal alteration of the electronic structure through Sn-Sn bond elongation and

关键词： X ray scattering

来源：评论

学校读者我要写书评

暂无评论

PHORTEX: Physically-Informed Operational Robotic Trajectories for Scientific Expeditions

Field Robotics

引用

Field Robotics 2025年 4卷 138-181页

作者： Victoria L. Preston Genevieve E. Flaspohler John W. Fisher Anna P. M. Michel Nicholas Roy Applied Ocean Physics and Engineering Massachusetts Institute of Technology and Woods Hole Oceanographic Institution Joint Program Cambridge MA 02139 Electrical Engineering and Computer Science Massachusetts Institute of Technology and Woods Hole Oceanographic Institution Joint Program Cambridge MA 02139 Computer Science and Artificial Intelligence Laboratory Massachusetts Institute of Technology Cambridge MA 02139 Applied Ocean Physics and Engineering Woods Hole Oceanographic Institution Woods Hole MA 02543

Mobile robots are increasingly used to collect valuable in situ samples during scientific expeditions. However, many phenomena of scientific interest—deep-sea hydrothermal plumes, algal blooms, warm-core eddies, and lava flows—are spatiotemporal distributions that evolve on spatial and temporal scales that complicate sample collection. Here, we consider the problem of charting the space-time dynamics of deep-sea hydrothermal plumes with the state-of-the-art autonomous underwater vehicle (AUV) Sentry. In the hydrothermal plume charting problem, the plume state is driven by complicated and unobserved dynamics in the deep sea. To effectively sample the moving plume, an autonomy system must infer plume dynamics from sparse, point observations, while respecting operational constraints of AUV Sentry that restrict the set of possible trajectories to nonadaptive, uniform-coverage patterns. We frame the plume charting problem as a sequential decision-making problem and formulate a mission planner PHORTEX (PHysically-informed Operational Robotic Trajectories for Expeditions) that strategically designs full mission trajectories for Sentry, where each mission plan is informed by the observations of the last. PHORTEX is composed of a trajectory optimizer, which maximizes expected samples collected within a moving plume, and PHUMES (PHysically-informed Uncertainty Models for Environment Spatiotemporality), a modeling framework that leverages an embedded simulator of idealized plume physics as an inductive bias to enable dynamics learning from extreme partial observations and a few Sentry deployments. In both simulation and in field trials at a hydrothermal site in the Gulf of California, we demonstrate that Sentry using PHORTEX learns to track a moving hydrothermal plume and gather samples that significantly improve upon baseline spatial and temporal diversity for use in downstream science tasks.

关键词： Trajectory Sensors Oceans Vehicle dynamics Robot sensing systems Adaptation models Spatiotemporal phenomena Decision making Marine robots Environmental monitoring Mobile robots

来源：评论

学校读者我要写书评

暂无评论

Demonstration of a new CLLBC-based gamma- and neutron-sensitive free-moving omnidirectional imaging detector

arXiv

引用

arXiv 2025年

作者： Vavrek, Jayson R. Pavlovsky, Ryan Negut, Victor Hellfeld, Daniel Joshi, Tenzing H.Y. Quiter, Brian J. Cates, Joshua W. Applied Nuclear Physics Program Nuclear Science Division Lawrence Berkeley National Laboratory 1 Cyclotron Road BerkeleyCA94720 United States

We have developed a CLLBC-based gamma- and neutron-sensitive multi-channel omnidirectional imaging detector, suitable for handheld or vehicle-borne operation and capable of quantitative radiation mapping in 3D. The system comprises 62 CLLBC modules in an active-masked configuration, and is coupled to a Localization and Mapping Platform (LAMP) suite of contextual sensors that provides a 3D map of the environment. The contextual and radiation data is combined using Scene Data Fusion (SDF) methods to better inform the reconstruction of the source radiation distribution from variations in the measured counts as the detector moves throughout the 3D environment. Here, we first present benchtop-scale characterization studies for both the neutron and gamma ray channels. In tandem, we present Geant4 simulations of both the single-crystal and full-system detection efficiencies over the omnidirectional field of view, and compare against validation measurements. We then demonstrate the imager’s capabilities in a variety of different scenarios, ranging from free-moving handheld simultaneous measurements of 137Cs and 252Cf to more challenging motion-constrained or static measurement scenarios. In several of these scenarios we also demonstrate how the full omnidirectional multi-crystal responses markedly improve the reconstruction quality. The imager is therefore a promising system for conducting simultaneous gamma and neutron radiation measurements in applications such as homeland security, contamination mapping, and nuclear decommissioning. Copyright © 2025, The Authors. All rights reserved.

关键词： Neutrons

来源：评论

学校读者我要写书评

暂无评论

A Mini-Review on Useful Strategies for Improving the Electrochemical Performance of Graphene for Supercapacitor Application

引用

JOM 2025年 1-17页

作者： Nkele, Agnes C. Alshoaibi, Adil Ezema, Fabian I. Department of Physics and Astronomy University of Nigeria Nsukka Nigeria Applied Physics Program Smalley-Curl Institute Rice University Houston USA Department of Physics College of Science King Faisal University Al Ahsa Saudi Arabia Africa Centre of Excellence for Sustainable Power and Energy Development University of Nigeria Nsukka Nigeria

The need for clean energy resources and immense energy availability during scarce periods has prompted the manufacture and large-scale production of energy conversion and storage devices. These technologies would mitigate global challenges for sustainable energy availability and improve environmental sustainability. Supercapacitors have emerged as useful charge storage systems for harnessing renewable energy resources and increasing energy storage capability. Graphene has exhibited exceptional qualities like high energy density and outstanding electrochemical properties, which make it a useful electrochemical material in supercapacitors and other energy storage devices (Rahman et al., in: Mubarak, Khalid, Walvekar, Numan (eds) Contemporary nanomaterials in material engineering applications, Springer, Cham, 2021; Raccichini et al. in Nat Mater 14:271, 2015). This review describes an overview of supercapacitors with the basic components and classifications. An overview of graphene usage as an electrochemical material is discussed in this work, with relevant literature highlighted in the different sections and sub-sections. Diverse methods of synthesizing graphene from graphite, graphene oxide, or their derivatives are also discussed with relevant reviews. Different strategies aimed at enhancing the electrochemical performance of graphene are described, and the overall relevance and future perspectives surrounding the use of graphene in electrochemical and energy storage systems have been highlighted.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Soft matter mechanics of immune cell aggregates

arXiv

引用

arXiv 2025年

作者： Askari, Shohreh Rubio, Guillem Saldo Datar, Anagha Harjunpää, Hedi Fagerholm, Susanna C. Backholm, Matilda Department of Applied Physics Aalto University Espoo Finland Research Program of Molecular and Integrative Biosciences Faculty of Bio- and Environmental Sciences University of Helsinki Helsinki Finland

T-cells are a crucial subset of white blood cells that play a central role in the immune system. When T-cells bind antigens, it leads to cell activation and the induction of an immune response. If T-cells are activated by antigens in vivo or artificially in vitro, they form multicellular aggregates. The mechanical properties of such clusters provide valuable information on different T-cell activation pathways. Furthermore, the aggregate mechanics capture how T-cells are affected by mechanical forces and interact within larger conglomerates, such as lymph nodes and tumours. However, an understanding of collective T-cell adhesion and mechanics following cell activation is currently lacking. Probing the mechanics of fragile and microscopically small living samples is experimentally challenging. Here, the micropipette force sensor technique was used to stretch T-cell aggregates and directly measure their Young’s modulus and ultimate tensile strength. A mechanistic model was developed to correlate how the stiffness of the mesoscale multicellular aggregate emerges from the mechanical response of the individual microscopic cells within the cluster. We show how the aggregate elasticity is affected by different activators and relate this to different activation pathways in the cells. Our soft matter mechanics study of multicellular T-cell aggregates contributes to our understanding of the biology behind immune cell activation. © 2025, CC BY.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Innovative metallization pattern and technique for industrial rear emitter p-type tunnel oxide passivated contact solar cells

引用

Journal of Industrial and Engineering Chemistry 2025年 147卷 628-635页

作者： Khokhar, Muhammad Quddamah Yousuf, Hasnain Rahman, Rafi Ur Aida, Maha Nur Madara, Polgampola Chamani Jony, Jaljalalul Abedin Dao, Vinh-Ai Pham, Duy Phong Yi, Junsin Department of Electrical and Computer Engineering Sungkyunkwan University Suwon16419 Korea Republic of Interdisciplinary Program in Photovoltaic System Engineering Sungkyunkwan University Suwon16419 Korea Republic of Department of Future Energy Engineering Sungkyunkwan University Suwon16419 Korea Republic of Department of Physics Faculty of Applied Sciences HCMC University of Technology and Education Ho Chi Minh City700000 Viet Nam College of Information and Communication Engineering Sungkyunkwan University Suwon16419 Korea Republic of

In this study, we aim to enhance the efficiency of p-type tunnel oxide passivated contact (p-TOPCon) solar cells by improving charge carrier extraction while achieving higher fill factor (FF) and open circuit voltage (Voc). We explore various potential methods for the photovoltaic industrial procedure, including optimizing metallization patterns and techniques, such as the utilization of a high efficiency grid pattern (HEGP) in place of the conventional straight finger-line pattern (SFLP). Co-firing conditions, peak firing temperature, and belt speed are investigated for their impact on FF enhancement, along with evaluating the effects of single and double print processes. Furthermore, we examine the efficacy of Nafion treatment as a surface modification technique to enhance FF. Experimental results indicate that optimizing co-firing conditions and employing Nafion treatment significantly increased FF to approximately 83.26% in p-TOPCon solar cells. Adjusting peak firing temperature and belt speed, as well as implementing the double print process, demonstrate superior FF enhancement compared to the single print process. Additionally, Nafion treatment contributes to FF improvement by passivating surface defects and enhancing charge carrier collection. Overall, this study provides valuable insights into optimizing co-firing conditions and surface treatment techniques to enhance p-TOPCon solar cell efficiency (Eff) up to 23.50%, thus advancing high-efficiency photovoltaic technology. © 2024 The Korean Society of Industrial and Engineering Chemistry

关键词： Metallizing

来源：评论

学校读者我要写书评

暂无评论

Projecting Assumptions: The Duality Between Sparse Autoencoders and Concept Geometry

arXiv

引用

arXiv 2025年

作者： Hindupur, Sai Sumedh R. Lubana, Ekdeep Singh Fel, Thomas Ba, Demba School of Engineering and Applied Science Harvard University United States CBS-NTT Program in Physics of Intelligence Harvard University United States Kempner Institute Harvard University United States

Sparse Autoencoders (SAEs) are widely used to interpret neural networks by identifying meaningful concepts from their representations. However, do SAEs truly uncover all concepts a model relies on, or are they inherently biased toward certain kinds of concepts? We introduce a unified framework that recasts SAEs as solutions to a bilevel optimization problem, revealing a fundamental challenge: each SAE imposes structural assumptions about how concepts are encoded in model representations, which in turn shapes what it can and cannot detect. This means different SAEs are not interchangeable—switching architectures can expose entirely new concepts or obscure existing ones. To systematically probe this effect, we evaluate SAEs across a spectrum of settings: from controlled toy models that isolate key variables, to semi-synthetic experiments on real model activations and finally to large-scale, naturalistic datasets. Across this progression, we examine two fundamental properties that real-world concepts often exhibit: heterogeneity in intrinsic dimensionality (some concepts are inherently low-dimensional, others are not) and nonlinear separability. We show that SAEs fail to recover concepts when these properties are ignored, and we design a new SAE that explicitly incorporates both, enabling the discovery of previously hidden concepts and reinforcing our theoretical insights. Our findings challenge the idea of a universal SAE and underscores the need for architecture-specific choices in model interpretability. Overall, we argue an SAE does not just reveal concepts—it determines what can be seen at all. Copyright © 2025, The Authors. All rights reserved.

关键词： Neural networks

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：